In the field of color photography, extensive studies have been conducted in an attempt to improve sharpness and color reproducibility. Development inhibitor-releasing couplers (called DIR couplers) have been the subject of some of these studies. As a result, various DIR couplers have been discovered. For example, known DIR couplers include those described in U.S. Pat. Nos. 3,227,554, 3,701,783, 3,615,506, and 3,617,291, and JP-A-52-82423 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"). With these DIR couplers, though, the development inhibitor which is released from the light-sensitive material on color development and diffused into a processing solution accumulates in the processing solution, and the processing solution comes to have an unfavorable development inhibitory effect as a result.
In order to overcome this problem, there has been a need to use a DIR coupler releasing a development inhibitor which, after diffusing into a color developing solution, is decomposed to a substance having no substantial adverse effect on photographic properties. Such DIR couplers have been described, for example, in U.S. Pat. No. 4,477,563. These couplers cause no contamination of the color developing solution, so they are suitable for use in continuous processing. In particular, malondianilide couplers disclosed in U.S. Pat. No. 4,477,563 have been used as DIR couplers because of their high coupling activity. However, the dye image produced from malondianilide couplers has poor resistance to humidity and heat. Some improvement has been made, as exemplified by the couplers disclosed in JP-A-2-28645 but the effects attained are insufficient and still require further improvement. In particular, when a DIR coupler is present in a photographic material in an increased amount, the dye image produced therefrom must have sufficient stability for maintaining its density.